I’m inclined to think that Ngannou having a very competitive and exciting fight with Gane would be best, maybe getting a knockdown or two in the early rounds and almost sealing the deal.
But Francis isn’t known for being a cardio machine and gassing would be almost expected if it got past the 3rd, so losing the later rounds to a recovered and 5 round experienced, more technical Gane wouldn’t be out of the realm of possibility.
Ngannou like during the first Stipe fight would hang on for dear life to make it to a decision, in the end Cyril Gane would win in a extremely back and forth, yet conflicted split decision fight.
Ngannou would maintain his appeal as the super dangerous Knockout Artist we’ve always known him for being, there would be no doubt about his heart and toughness as well as being resilient enough to keep his head barely above water until the end regardless of being completely cardiovascularly spent.
He would’ve fulfilled his contract with the UFC, drawn more eyes to an incredible fight even after the fact, maintained most of his aura, yet doesn’t suffer too much backlash from the loss because we always knew he was never built to fight and maintain being dangerous over an entire 5 round fight.
He can leave the UFC with his head High saying that he actually won the fight and was closer to ending it thus impartial and tampered with judges is to blame... which is quite believable considering some of the decisions we’ve seen specifically with the Jones and DJ fights. Francis can go and box while still maintaining most of his appeal for being MMA’s most dangerous KO King.